U.S. Pat. No. 4,638,445 discloses a mobile platform which is able to move about autonomously. To prevent the platform from striking obstacles as it travels it has arrays of sensors of two kinds. The first sensor array is adapted to detect obstacles situated near to the mobile platform, whereas the second sensor array is adapted to detect far-off obstacles.
EP 2 407 281 B1 discloses a mobile robot having an autonomously mobile chassis and a robot arm mounted thereon. The robot is suited to changing its location automatically in order to perform tasks at different points. The robot may also have a camera which can be used for monitoring for collisions between the robot arm and its surroundings. The document does not say anything about possible reactions by the robot arm if a risk of collision is found in the course of the monitoring.
If the risk of collision is with a human being, the only reaction that is possible is for the entire robot to make an emergency stop. Because the robot cannot predict the next movement by the human being, the only option it has is to come to a standstill in order to reduce the risk of a collision or, if the collision cannot be prevented, to minimise the impetus behind the impact.
If the robot is moving autonomously between stationary obstacles, a risk of collision which exists can be reliably averted by an emergency stop. However, any emergency stop makes a human intervention necessary to remove the cause of the risk of collision and to put the robot back into operation.
WO 2013/171905 A1 (see also US 2015/0160654 as a document in the same family but a post-publication) discloses a mobile robot which is able to sense obstacles, meaning, in this case, passers-by. To prevent a collision with a passer-by, the robot is able to hold a warning means carried by a robot arm into the passer-by's field of vision and to emit a warning signal, to request the passer-by to move out of the way.
WO 2012/149446 A2 discloses a controllable robot having two robot arms. The robot has input means by means of which a user is able to displace the robot and operate the robot arms.
WO 2015/0063972 A1 discloses a mobile robot having a robot arm which is designed to unload cartons automatically from a carton pile onto a conveyor belt.
DE 10 2013 109876 A1 discloses an industrial robot having a permanently installed robot arm. The robot is adapted to control the robot arm in such a way that obstacles can be bypassed.